One of the most celebrated traditional holidays in Vietnam is Vietnamese Teacher's Day, which falls on the twentieth of November every year.

People celebrate this special day to honor all Vietnamese teachers for their devotion to the education. On this merry and grateful occasion, students often visit their teachers, wishing them good health, happiness, and career success and respectfully presenting them gifts like flowers to show their gratitude to their teachers. Gift shops are filled with beautiful 20-11 gifts and many students get excited to choose ones for their teachers. And those who are out of town and cannot visit their teachers often send their favorite teachers greeting cards on which words of gratitude and wishes of the season are expressed. Many alumni who are now successful businessmen and government officers often offer very big bunches of flowers to their old schools as an expression of their gratitude towards their teachers who have taught them to become useful citizens.

Both teachers and students are very happy on this interesting holiday because they have a chance to recall their funny and good memories. Vietnamese Teacher's Day is really one of our most important holidays.

Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions. He _______ a letter when the telephone rang.